Fig. 5.

Effects of FAK-Tyr⁴⁰⁷ mutations on the actin cytoskeleton and the localization of BTB constituent proteins in Sertoli cells in vitro. Sertoli cells (0.04 × 10⁶ cells/cm²) cultured for 2 d were transfected with Cy3-labeled plasmid DNA of pCI-neo vector only vs. various FAK constructs (red). Two days thereafter, cells were fixed and processed for F-actin staining (i–iv; green) or immunofluorescence staining of Arp3 (v–viii; green), Eps8 (ix–xii; green), claudin-11 (xiii–xvi; green), or ZO-1 (xvii–xx; green). Nuclei were visualized with DAPI (blue). Overexpression of both WT FAK and FAK Y407E caused up-regulation of cortical actin and Arp3 at the cell-cell interface (arrowheads in ii, iv, vi, and viii) and the appearance of Arp3-rich “precipitates” in the cell interior (annotated by asterisks in vi and viii), whereas overexpression of FAK Y407F caused mislocalization of TJ proteins claudin-11 and ZO-1, moving away from the cell-cell interface into the Sertoli cell cytosol (white brackets in xv and xix), showing signs of protein internalization. (Scale bar: 30 μm.)